That is one way to skin a cat.
I'd run two separate -8an supply lines, one from each pump to each side of the rail, other side of the rail to the fpr. if you still needed a third pump, i'd run another -8an line from the pump straight to the fpr with a one way check valve on a hobbs switch. fuel pressure shouldn't spike too bad since its feeding straight into the fpr.
See if you can get your hands on a triple y-block instead for your setup, I know those y-block cost a pretty penny!
http://www.nukeperformance.com/produ...block-x-block/
more goodness:
http://www.theturboforums.com/thread...re-if-you-know
-Carl